The influence of phonon anharmonicity on thermal and elastic properties of neptunium

Abstract

a b s t r a c tA self-consistent thermodynamic model describing the thermal and elastic properties of a-and b-phases of neptunium was developed. The presence of strong phonon anharmonicity of Np is established. The obtained results are in good agreement wit h the experimental data and enabl e to predict the Np properties in wide temperature range.

Phonon anharmonicity of iron monosilicide

“…[15,16]. Since in the present study a compound is considered, one has to build a generalization of this model to the case of several different atoms in the unit cell.…”

A thermodynamic model of thermal end elastic properties of curium

“…One can see that Debye temperature of Cm is essentially lower than Debye temperature of Gd, which according to [8] is of about 170 K. The bulk modulus of Cm rather weakly depends on temperature as compared with e.g. Np [6] and d-Pu [7], which indicates that Cm can be characterized by relatively weak phonon anharmonicity. This fact is confirmed by the calculated contribution of phonon anharmonicity to the heat capacity of Cm and by the values of…”

“…In Table 1 we compare the parameters characterizing the degree of phonon anharmonicity of curium (the present study), neptunium [6], gadolinium and lutetium [8] -the latter two being representatives of the lanthanide (4f metals) series. It follows from Table 1 that phonon anharmonicity of Cm although being weaker than of Np, manifests in Cm stronger than in Gd and is almost the same as in Lu.…”

“…Following [6][7][8] we consider the connection of Debye temperature h with molar volume V and bulk modulus B in the form…”

“…In the present study a simulation of temperature dependences of the thermal and elastic properties of Cm is carried out in terms of the self-consistent thermodynamic model [6][7][8], which along with the lattice properties accounts for the effect of electronic subsystem.…”